The present invention relates generally to switching of communication signals, e.g., integrated services digital network (xe2x80x9cISDNxe2x80x9d) signals. A preferred embodiment of the present invention is an automatic ISDN switch that automatically detects the presence of an ISDN device at one of a plurality of locations and automatically routes all audio, video, and data to that one location while locking out all of the other locations connected to the switch. The ISDN switch of the present invention has numerous applications, including by way of example videoconferencing using a 128 kbps (128,000 bits per second), 256 kbps, 384 kbps, or 512 kbps ISDN configuration.
Videoconferencing has recently undergone an evolution. Prior to this evolution, videoconferencing equipment was typically semi-permanently installed in a dedicated location with dedicated, permanently installed communication lines. The recent evolution took the form of making videoconferencing equipment mobile. In the past few years, most videoconferencing equipment on the market has been marketed as being mobile and by far the majority of videoconferencing systems sold over the past few years have been mobile systems.
There are a number of standard communications methodologies that can be used in videoconferencing. Currently, the most widely used videoconferencing communications medium in the United States and internationally is ISDN, which is the basis for a number of different specific communications configurations. One ISDN videoconferencing communications family of standards is known as H.320 (ITU-T) promulgated by the International Telecommunications Union (formerly known as CCITT). One implementation allows 384 kbps transmission of information using three individual ISDN-BRI (Integrated Services Digital Network-Basic Rate Interface) telephone lines. This form of videoconference transmission is also known or described as xe2x80x9csix-channel transmissionxe2x80x9d in the videoconference industry, because it uses six ISDN channels, each of which carry 64 kbps of digital information. Each ISDN-BRI telephone line includes two separate 64 kbps lines or channels, as they are referred to in the videoconferencing industry. The H.320 standard encompasses video (e.g., videoconferencing), audio, and control using one or more 64 kbps ISDN lines. A majority of corporate videoconferencing installations currently use six 64 kbps ISDN lines, using three two-channel ISDN-BRI lines; while other applications such as medical videoconferencing applications use as many as eight 64 kbps ISDN lines.
One obvious benefit of using mobile ISDN videoconferencing equipment is that one videoconferencing unit can be used at a number of locations in the same facility. However, connecting ISDN devices to an ISDN line is complicated by the fact that ISDN lines must be properly terminated with an industry standard network U-interface, such as an NT-1, an NT-3, or a Triple NT-1. Only a single device (more specifically a U-interface) may be connected to a BRI line. Businesses requiring use of ISDN lines in more than one location have had two acceptable prior art options: (i) installing multiple data lines for each possible location or (ii) installing a patch panel at the point of termination with which one can physically manipulate the termination point of the ISDN line(s). A third prior art option, daisy-chaining, is not an acceptable option because it has problems of signal quality consistency, security, and accessibility, as will be discussed below.
The first prior art option, installing multiple data lines for each possible location, is very costly and inconvenient. One implementing the first prior art option would be charged for the installation of each set of three ISDN lines (recall that with the majority of corporate or industrial videoconferencing installationsxe2x80x94as compared to typical home usagexe2x80x94each location requires access to three two-channel BRI telephone lines), the digital monthly services charges for each set of three ISDN lines for each location, even when lines are not used, and the cost of the (3) CAT-5 wires to each location beyond the initial point of termination. Thus, to implement this first option using current wiring standards, it is necessary to run multiple data lines from the point of presence (the phone room in typical installations) to each possible destination. If, for example, a 384 kbps ISDN configuration were to be needed in 3 different rooms, it would be necessary for a total of 9 data lines be run (3 ISDN 2 channel lines from point of presence to destination). The cost and type of cabling must be considered for such an implementation; expensive CAT-5 or CAT-6 wiring is specified. The cost of this option can become prohibitive with only a few locations. Moreover, under these stringent installation methods, flexibility of conference locations is not an option due to the fact that the wiring must be permanently installed.
Additionally, the first prior art option is inconvenient to use with a mobile videoconferencing unit. As known to those in the art, each videoconferencing system has an ISDN network interface (e.g., an NT-1, an NT-3 or an Triple NT-1) that acts to terminate the ISDN line(s) used in that system and an ISDN video codec. Each 64 kbps ISDN line has its own unique telephone number. As also known to those in the art, the ISDN video codec must be programmed with the telephone number(s) for each ISDN line(s) used. Thus, moving a mobile videoconferencing unit from one location to another requires that six telephone numbers be programmed into the ISDN video codec, which typically must be done by busy MIS personnel. At least one ISDN video codec in the art, i.e., a unit from Polycom Inc., includes software that attempts to automatically detect the phone numbers associated with the ISDN lines and program those numbers into the video codec. However, this autodetection process can take 5-10 minutes and is not always successful; the system might fail to detect the telephone numbers. Also, executing the autodetection process still typically requires MIS personnel to perform.
The second prior art option is to install a patch panel in the telephone closet or another location with which one can physically manipulate the termination point of the ISDN line(s). This option has a great deal more flexibility than the first option, in that one can wire multiple rooms for access and simply xe2x80x98patchxe2x80x99 the data lines to the destination at the time of need; however, it suffers from relatively high cost and is inconvenient as well.
More specifically, the second option requires that all communication lines be brought to the point of presence and terminated in a patch bay. Located near the incoming patch bay, typically underneath, is a patch panel. Simply put, the electrical connection between the patch bay and the patch panel resembles the old switchboard banks that telephone operators would use to directly electrically connect a caller to a destination. The same antiquated manual process used to route telephone calls, before and during the 1950""s is currently used to route ISDN lines with the patch panel. Because ISDN technology requires termination at each end to properly operate, the patch panel routes the ISDN lines to a single termination point and isolates all other signal access locations. The patch panel has the benefit of giving the user security, in that the data lines can only be connected to a single destination; therefore, eavesdropping through another room is not possible. Another advantage of the patch bay over the first prior art option is that there is flexibility in provisioning data lines; more data lines can be added without changing the wiring plant. In the alternative, manual switches are used instead of the manual patch panel in this prior art option.
There are difficulties with the patch panel method of connecting ISDN lines as well. One of the primary drawbacks of using a patch panel to route ISDN lines to various destination locations is inconvenience. Switching the ISDN lines from one location to another requires that a technically capable person be notified and available, in advance, when and where an ISDN line is needed so that the appropriate cables can be manually connected or switched ahead of time. Another primary concern is cost of implementation. It is still necessary for a videoconferencing application implemented with this second option, using current videoconferencing wiring conventions, to run multiple data lines to each possible location. Yet another concern is that an error in patching can prevent the system from functioning at all.
One common method of connecting multiple devices to a single line, daisy-chaining, is not a realistic option for ISDN lines, because of termination issues. This issue can be understood in contrast to the plain old telephone system (POTS).
In a normal home telephone environment, using POTS telephone lines, it is common practice to attach multiple telephones to a single line by connecting them one to another in a daisy chain format. Daisy-chaining devices causes several potential problems, such as an obvious decrease in sound volume. This is acceptable when using ordinary telephones connected to POTS telephone lines because human ears are much more flexible and less demanding than computer equipment, i.e., our ears can still understand what is being said despite changes in signal quality and volume caused by daisy-chaining. The termination point can be at any telephone connected to the POTS telephone line, and can change from usage to usage as different handsets are used. Thus, with ordinary telephones connected to POTS telephone lines, the termination (or end point of the wire) does not have to be defined in advance as long as certain minimum requirements are made (e.g., limiting the total number of devices daisy chained together). In addition to changes in signal quality and volume, daisy-chaining causes other problems. For example, when a conversation is taking place on the telephone, it is possible to eavesdrop by picking up another extension. Another concern is that a physically damaged wire or jack can prevent all telephone sets after that point from functioning.
These problems with daisy-chaining are a great deal more pronounced with a digital protocol, such as ISDN. The signal sensitivity in a digital line must be constantly maintained in order for accurate and consistent data transmissions to take place. If, during a videoconferencing session at one location, another videoconferencing unit is connected to the same ISDN line, the signal loss caused by that other connection being made (made possible only because of the inadvised use of daisy-chaining) may cause one or more channels to be lost, or the entire call to be disconnected. Also, ISDN lines must have a fixed, predetermined termination point. Unlike the procedure for ordering a standard home telephone line, when provisioning (or ordering) a digital ISDN line one is required to specify a single termination point for that ISDN line for the installation to occur.
According to the present invention, an automatic ISDN switch is provided that avoids the need for patch panels, costly dedicated ISDN lines to all locations, and use of MIS personnel to switching patch panel wires. The present invention also includes a novel wiring configuration that significantly reduces the cost of wiring ISDN installations.
According to one aspect of the present invention, an automatic ISDN switch automatically determines the location of the target videoconferencing location and switches the incoming ISDN lines to the target location without requiring any manual routing of ISDN lines. The ISDN switch of the present invention comprises a switch bank in circuit communication with a control unit. In short, the control unit determines to which location the ISDN line(s) from the telephone company should be switched, and the switch bank switches the ISDN line(s) from the telephone company to a particular location. In a first embodiment, the control unit comprises autodetect logic that automatically detects the location of videoconferencing equipment and transmits a signal to the switch bank indicating to which location signal the ISDN line(s) from the telephone company should be switched. The autodetect logic can use any number of ways of detecting the location to which the ISDN line(s) from the telephone company should be switched, including by way of example, but not of limitation, detecting that a connector has been inserted into a receptacle, detecting that two conductors have been electrically shorted, detecting that the impedance between two conductors has changed, detecting that the electrical characteristics of at least one conductor have changed, detecting that videoconferencing equipment at a particular location has been powered up, a particular telephone extension being dialed from the particular location, etc. The control unit can be connected to the various locations by any suitable connection, e.g., by way of example but not of limitation, via one or more of the following circuit communications means: one or more conductor(s), connector(s), computer network(s), fiber optic link(s), optical signals(s), radio signal(s), electromagnetic signal(s), telephone line(s), sonic link(s), ISDN lines, hybrid ISDN lines, existing Ethernet cable(s), power line(s) (using, e.g., an X-10 interface), etc.
In a second embodiment of the present invention, the control unit comprises a communication circuit supporting a communications link to a communications device to allow a user to directly select the location to which the ISDN line(s) from the telephone company should be switched, including by way of example, but not of limitation: a keypad located in one or more locations to which ISDN line(s) from the telephone company could be switched (e.g., videoconferencing locations), a pass key reader in one or more of the locations, a keypad located on the enclosure for the control unit and/or the switch bank, a keypad at a location different from where the control unit and/or switch bank are located and different from the one or more locations, a telephone extension through which a user might select the particular location, a computer terminal through which a user might select the particular location, a web site through which a user might select the particular location, an electromagnetic link through which a palmtop computer might be used to select the desired location, etc. The control unit can be connected to the communications device by any suitable connection, e.g., by way of example but not of limitation, via one or more of the following circuit communications means: one or more conductor(s), connector(s), computer network(s), fiber optic link(s), optical signal(s), radio signal(s), electromagnetic signal(s), telephone line(s), sonic link(s), ISDN lines, hybrid ISDN lines, existing Ethernet cable(s), power line(s) (using, e.g., an X-10 interface), etc.
Any combination of one or more of the implementations of the first embodiment can be combined with any combination of one or more of the implementations of the second embodiment to provide enhanced functionality.
According to the novel wiring configuration of the present invention, two or more ISDN lines are used with a single cable. In one embodiment, a plurality of ISDN-BRI lines are combined on a single hybrid line to provide enhanced throughput. These lines are xe2x80x9chybridxe2x80x9d in the sense that they ignore industry standard wiring conventions (ATandT Bell Laboratories Std. No. 568-B for videoconferencing) for CAT-5 and CAT-6 wiring used in an ISDN videoconferencing application; i.e., more than one ISDN-BRI line is passed through a single CAT-5 or CAT-6 single cable. In the case of a 384 kbps videoconferencing system, the three ISDN-BRI lines (six 64 kbps lines) can be passed through six of the eight available conductors in a CAT-5 or CAT-6 cable (or a cable suitable for Ethernet applications), leaving two lines for the autodetect logic and/or the communication circuit in the control unit. The novel wiring convention of the present invention arose out of an awareness that, using wiring conventions for videoconferencing, a major impediment to the marketing and installation of videoconferencing systems is the cost and complexity associated with installing new wiring required with typical videoconferencing installations. This awareness, coupled with a knowledge that most conference rooms and offices are wired with a single unshielded twisted pair (xe2x80x9cUTPxe2x80x9d, which actually has four such twisted pairs) cable for Ethernet applications, and that that Ethernet cable is rarely used in conference rooms, and further coupled with insight that UTP cables suitable for Ethernet applications would also be suitable for a plurality 64 kbps ISDN lines in violation of vidoeconferencing wiring conventions, led to the concept of using the hybrid ISDN lines of the present invention. Thus, according to the present invention, existing UTP wiring found in most conference rooms could be used as-is for 384 kbps or 512 kbps videoconferencing applications.
The novel wiring configuration of the present invention can be used for any number of applications requiring more than two 64 kbps ISDN lines. For example, in the case of a 512 kbps medical application, four ISDN-BRI lines (eight 64 kbps lines) can be passed through the eight available conductors in a CAT-5 or CAT-6 cable (or cable for Ethernet applications), and the autodetect logic and/or the communication circuit in the control unit must use another communication path (e.g., telephone lines, RF signal, etc.) to either autodetect or receive a communication about the desired location, unless some of the eight available conductors in the CAT-5 or Ethernet cable are used for both detection and the ISDN signals.
It is therefore an advantage of the present invention to provide an ISDN switch that does not require human intervention in the form of manually switching one or more ISDN lines to a particular location.
It is therefore another advantage of the present invention to provide an ISDN switch that automatically detects a location requiring the use of one or more ISDN lines.
It is a further advantage of this invention to provide an ISDN switch that automatically detects a location requiring the use of one or more ISDN lines and that automatically switches the ISDN lines to that location without requiring any manual routing, patching, or switching of ISDN lines.
It is yet another advantage of the present invention to allow a significant cost savings by using hybrid ISDN lines in which more than one ISDN signal is passed through a single ISDN cable.
It is still another advantage of the present invention to allow a significant cost savings by using hybrid ISDN lines in which more than one ISDN signal is passed through an existing cable for use in an Ethernet application.
It is further still another advantage of the present invention to allow a significant cost savings by allowing all three ISDN-BRI lines in a 384 kbps videoconferencing application to be passed through a single CAT-5 or CAT-6 cable.
These and other advantages of the present invention will become more apparent from a detailed description of the invention.